U.S. patent application number 17/297014 was filed with the patent office on 2022-01-27 for device for pressing flat material.
The applicant listed for this patent is AZL AACHEN GMBH, Rheinisch-Westfalische Technische Hochschule (RWTH) Aachen. Invention is credited to Michael Emonts, Richard Schares, Thomas Weiler, Albert Wendt.
Application Number | 20220024158 17/297014 |
Document ID | / |
Family ID | 1000005953787 |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220024158 |
Kind Code |
A1 |
Wendt; Albert ; et
al. |
January 27, 2022 |
DEVICE FOR PRESSING FLAT MATERIAL
Abstract
The invention relates to a device for pressing flat material,
comprising means for transporting the flat material (15) in a
transport direction and at least one pressing roller pair (9),
which is stationary in the transport direction and acts on the flat
material (15) on both sides, said device being characterized in
that both pressing rollers (13, 14, 29, 34) of the pressing roller
pair (9) or both pressing rollers (13, 14, 29, 34) of at least one
of the pressing roller pairs (9) are elastically deformable in the
radial direction at least at the circumference of said pressing
rollers.
Inventors: |
Wendt; Albert; (Hannover,
DE) ; Emonts; Michael; (Aachen, DE) ; Schares;
Richard; (Aachen, DE) ; Weiler; Thomas;
(Aachen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AZL AACHEN GMBH
Rheinisch-Westfalische Technische Hochschule (RWTH) Aachen |
Aachen
Aachen |
|
DE
DE |
|
|
Family ID: |
1000005953787 |
Appl. No.: |
17/297014 |
Filed: |
November 27, 2019 |
PCT Filed: |
November 27, 2019 |
PCT NO: |
PCT/DE2019/101018 |
371 Date: |
May 26, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 70/54 20130101;
B29C 2043/5808 20130101; B29C 43/245 20130101; B29C 43/46 20130101;
B27N 3/24 20130101; B29C 70/504 20130101; B29C 2043/461 20130101;
B29C 43/58 20130101; B29C 43/52 20130101 |
International
Class: |
B29C 70/50 20060101
B29C070/50; B29C 70/54 20060101 B29C070/54; B29C 43/58 20060101
B29C043/58; B29C 43/52 20060101 B29C043/52; B29C 43/46 20060101
B29C043/46; B29C 43/24 20060101 B29C043/24; B27N 3/24 20060101
B27N003/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2018 |
DE |
10 2018 130 019.0 |
Claims
1.-17. (canceled)
18. A device for pressing processing flat material, comprising
means for transporting the flat material in a transport direction
and at least one pressing roller pair which is stationary in the
transport direction and acts on the flat material on both sides,
characterized in that, both pressing rollers of the pressing roller
pair or both pressing rollers of at least one of the pressing
roller pairs are elastically deformable in the radial direction at
least at the circumference of said pressing rollers.
19. The device according to claim 18, characterized in that there
are at least two pressing roller pairs arranged one behind the
other in the transport direction.
20. The device according to claim 18, characterized in that the
device is a double-belt press.
21. The device according to claim 18, characterized by heating
means for heating the flat material.
22. The device according to claim 21, characterized in that the
heating means act indirectly on the flat material via a double-belt
press.
23. The device according to claim 21, characterized in that at
least a number of the heating means act inductively.
24. The device according to claim 23, characterized in that at
least a number of the heating means are designed to generate
magnetic fields which have a predominant magnetic field component
oriented perpendicular to a center plane of the flat material.
25. The device according to claim 21, characterized in that the
heating means or at least a number of the heating means have a
meandering course at least in sections.
26. The device according to claim 21, characterized in that at
least a number of the heating means are designed to encompass a
section of the fiat material to be heated in a shape.
27. The device according to claim 21, characterized by means for
controlling or regulating a distance between the heating means and
a center plane of the flat material running parallel to the
transport direction and parallel to the axes of rotation of the
pressing rollers.
28. The device according to claim 21, characterized by spacers to
ensure a constant distance between the heating means and a center
plane of the flat material running parallel to the transport
direction.
29. The device according to claim 18, characterized in that at
least two pressing roller pairs can be acted upon in a controllable
or regulatable manner with different pressing forces.
30. The device according to claim 18, characterized in that at
least one of the pressing rollers of at least one pressing roller
pair comprises a cavity for the passage of a cooling fluid.
31. The device according to claim 18, characterized in that at
least one of the pressing rollers of at least one roller pair is
protected on the outer circumference by a heat-insulating
layer.
32. The device according to claim 31, characterized in that the
heat-insulating layer is part of the pressing roller.
33. The device according to claim 31, characterized in that the
heat-insulating layer is formed by a separate belt guided around
part of the circumference of the roller.
34. The device according to claim 18, characterized by cooling
means which, during use, direct a cooling fluid from the outside
onto the circumference of the pressing roller and/or onto the end
faces of the pressing roller.
Description
[0001] The invention relates to a device for pressing processing
flat material according to the preamble of claim 1.
[0002] Such devices can be used, for example, for pressing
processing, particularly for continuous lamination and/or
impregnation of flat material lines or material segments. In this
case, heating elements that heat the flat material for the pressing
processing can also be provided. The device can be, for example, a
double-belt press which is used, for example, for the production of
fiber-reinforced plastics.
[0003] A device of the type mentioned at the beginning is known
from EP 2 540 475 B1. This is a double-belt press in which two
endless steel belts are driven and pressed against one another with
their respective working strands, wherein the material to be
processed is guided and pressed between the steel belts in the
transport direction. The steel belts and thus indirectly the flat
material to be pressed are heated for processing by means of
inductive heating elements. The flat material is a composite
material made of thermoplastic and filaments. In the transport
direction behind the heating elements, a cooling unit comprising
press rolls is provided, which presses on the top side and bottom
side of the fiat material via the steel belts. Cooling water flows
through at least one of the press rolls for the purpose of cooling.
When using the double-belt press, the inductive heating elements
encompass the two steel belts in the heating region. The heating
elements are designed such that they comprise a lower half and an
upper half which are temporarily separable from one another at
connection points and thus allow an opening movement of the working
strand of at least one of the steel belts. The press rolls create a
line contact with the steel belt and thus an application of
pressure that is very limited in time and place.
[0004] EP 0236905 B1 discloses a device for applying a surface
pressure to advancing workpieces, which also constitutes a
double-belt press. The pressing power is generated here by pressure
plates which are arranged on both sides of the respective working
strand of the press belts. The transport of the flat material is
made possible by closed tracks of roller strands, which are guided
between the respective pressure plate and the associated press
belt, roll on the pressure plates and thereby transport the press
belt and the workpiece clamped between the press belts. It is
proposed that the rollers on each roller strand are positively
and/or non-positively connected to one another, enclose an axle rod
having a large annular gap exceeding a bearing play and are
elastically deformable up to the axle contact on the axle rod. The
elastic deformability of the rollers can compensate for tolerances.
In addition, the aforementioned annular gap can have a
heat-insulating effect to protect the axle rod if the pressure
plates are heated or cooled. The way in which active heating could
take place is not depicted in this prior art.
[0005] A double-belt press is known from DE 24 14 762 C2, in which
a plurality of press roll pairs are provided, the gap distance of
which can be varied, allowing the flat material to pass through.
The gap distance is regulated via a pressure that is regulated by
means of a pressure measuring device in a calibration section of
the double-belt press. The steel belt can be heated by means of
sliding shoes which slide on the respective steel belt and which
are each arranged between two press roll pairs. The sliding shoes
cause abrasion and thus increase the wear and tear on the
double-belt press.
[0006] WO2010/031364 Al discloses a device for the production of
composite material components, in which a rolling roller-shaped
pressure unit having an elastically flexible pressure pad presses
on the belt-shaped workpiece lying on a solid background, wherein
the workpiece is heated with laser radiation immediately before
being pressed on. A pressing roller pair having pressing rollers
working against one another is not disclosed. Special measures are
provided to protect the pressure pad from overheating by incident
laser radiation, such as a material of the pressure pad that is
(partially) transparent to laser radiation, a shadowing of the
pressure pad against the laser radiation or a cooling fluid passed
through the pressure pad. The elastic, flexible pressure pad is
used here to compensate for height differences on three-dimensional
workpiece surfaces when applying belt material.
[0007] The invention is based on the technical problem of providing
a device of the type mentioned at the beginning which enables a
more favorable pressure distribution of he pressing rollers acting
on the flat material.
[0008] In a device of the type mentioned at the beginning, this
object is achieved by the characterizing feature of claim 1.
Preferred embodiments of the device according to the invention
emerge from the dependent claims.
[0009] According to claim 1, a device for pressing processing flat
material, comprising means for transporting the flat material in a
transport direction and at least one pressing roller pair, which is
stationary in the transport direction and acts on the flat material
on both sides, said device being characterized in that both
pressing rollers of the pressing roller pair or at least one of the
pressing roller pairs are elastically deformable in the radial
direction at least at the circumference of said pressing
rollers.
[0010] Compared to the hard pressing rollers known from the prior
art for stationary pressing roller pairs, the elastic deformability
causes the press force to be distributed over a larger surface.
Compared to the line contact known from known steel rolls or steel
pressing rollers, said surface pressure results in an increased
pressure application time and thus an improved and more homogeneous
pressing effect.
[0011] Compared to the use of fluidic pressure pads, which can also
create a flat pressure zone, the outlay on equipment is
significantly lower and sealing systems that wear heavily are
avoided. The likewise conceivable creation of flat pressure zones
through the use of sliding plates would result in very limited
process pressures and increased wear. According to the invention,
on the other hand, surface pressure is made possible despite the
rolling movement of the pressing rollers.
[0012] The device according to the invention can advantageously be
designed such that there are at least two pressing roller pairs
arranged one behind the other in the transport direction. The
device according to the invention is particularly advantageous when
it is designed as a double-belt press. In this case, the at least
one pressing roller pair acts indirectly, namely via one of the
belts on the flat material. The elastic deformability of the
rollers of the at least one pressing roller pair is gentle on the
belts used, without losing the advantage of surface pressure
compared to pure line contact. In the case of the double-belt
press, in which at least one of the belts is usually driven, the
belt pair and the at least one pressing roller pair form the means
for transporting the flat material to be processed.
[0013] The device according to the invention can also comprise at
least one heating element for heating the flat material. Heating
elements are typically used for producing composite materials or
for lamination. One or more heating elements can be useful for the
invention. Even when the heating elements are mostly mentioned in
the plural in the following presentation of the invention for
linguistic simplification, the invention also relates to
corresponding design variants having only one heating element.
[0014] In the case of a double-belt press, the heating elements can
act indirectly on the flat material via the belts of the
double-belt press. Inductive heating is preferably used. One or a
plurality of inductors are preferably arranged on both sides of the
flat material, in the case of the double-belt press, on both sides
of the working strands of the press belts.
[0015] The device according to the invention can also be designed
such that at least a number of the heating means are designed to
generate magnetic fields which have a predominant magnetic field
component oriented perpendicular to a center plane of the flat
material. This can be implemented by means of a flat inductor
having a corresponding effect or a similarly constructed inductor
with a corresponding effect. For example, it can be provided that
the heating means or at least a number of the heating means have a
meandering course at least in some sections. The meandering course
can be aligned such that the loops of the meander run parallel to
the center plane of the flat material to be heated during use.
[0016] Furthermore, it can be provided that at least a number of
the heating means are designed to encompass a section of the flat
material to be heated in a U-shape. In this case, the inductors can
be designed such that they can be pushed into a working position
over a longitudinal side of the flat material. A complete enclosure
of the flat material is not given, which is why a relative movement
of two parts of the same inductor associated with an opening and
closing of electrical contacts to one another is not required.
[0017] The effect of the heating element on the goods to be heated
can depend considerably on the distance to the goods, this
particularly applies to inductive heating with its interaction with
the inductively coupled material. The latter can be the flat
material to be processed. In the case of the double-belt press,
however, the induction currents are usually generated in the belt
material of the double-belt press, which in turn conductively heats
the flat material to be processed. The elastic deformability of the
pressing rollers of at least one of the pressing roller pairs can
lead to the position of a center plane of the flat material running
parallel to the transport direction and parallel to the axes of
rotation of the pressing rollers shifting perpendicular to said
center plane. The shift can take place, for example, when, during
pressure build-up, the position of the axis of rotation of one of
the pressing rollers of a pressing roller pair in the device
remains constant while the axis of rotation of the other pressing
roller is shifted.
[0018] In order to be able to ensure the best possible reproducible
heating of the flat material, it can be particularly advantageous
to design the device according to the invention such that means are
provided which enable the position of the at least one heating
element to be adapted to the position of the center plane.
[0019] Such an adaptation can take place by passive tracking of the
at least one heating element, for example, by means of spacers
between the flat material or the associated belt of the double-belt
press and the at least one heating element. Such a spacer can be
effected, for example, via a rolling or sliding distance element.
At the same time, elastically acting forces can press the at least
one heating element in the direction of the flat material or the
associated belt of the double-belt press. Guide means can be
provided in order to avoid a displacement of the heating elements
parallel to the central plane of the flat material.
[0020] However, it can also be advantageous to design the device
according to the invention such that the distance between the
heating elements and the center plane of the flat material is
implemented by means for controlling or regulating this distance,
Said means can comprise, for example, electric motors and linear
guides, wherein the control or regulation are able to be based on
sensor values from distance sensors which determine the position of
the center plane relative to the axes of rotation of the pressing
rollers. This has the advantage that, unlike the passive spacers,
changes in the distance can be deliberately brought about in order
to be able to additionally influence the degree or the manner of
heating.
[0021] It can also be advantageous to design the device according
to the invention such that at least two pressing roller pairs can
be acted upon in a controllable or regulatable manner using press
forces that differ from one another. Different pressure profiles
can be set in this way, for example, with pressures that change
over the course of the pressing region.
[0022] The device according to the invention can also be designed
such that at least one of the rollers of at least one roller pair
comprises a cavity for the passage of a cooling fluid. This
protects the elastic material on the circumference of the pressing
rollers against potentially harmful high temperatures.
[0023] Furthermore, it can be advantageous to design the device
according to the invention such that at least one of the pressing
rollers of at least one pressing roller pair is protected on the
outer circumference by a heat-insulating layer. This provides a
further effective protection of the respective pressing roller
against the influence of the temperature of the flat material or
the belt of the double-belt press. The heat-insulating layer can be
a fixed component of the pressing roller. Alternatively, however,
the heat-insulating layer can also be formed by a separate band
guided around a partial circumference of the roller. This has the
advantage that the heat-insulating layer can easily be exchanged
and/or, as it rotates, can be guided through a cooling zone spaced
apart from the pressing roller. The materials for the
heat-insulating layer or the heat-insulating belt can be, for
example, textile structures, for example, made of glass, carbon,
aramid, basalt or high-performance elastomers such as Kalrez.RTM.
from DuPont.TM., or coated metal belts. Low thermal conductivity,
high temperature resistance, pressure and abrasion resistance and
elasticity at least in the circumferential direction of the
pressing roller are advantageous. The latter is particularly
advantageous when a deformation of the elastically deformable layer
leads to a change in the circumference thereof, which the
heat-insulating layer must follow.
[0024] Finally, the device according to the invention can be
designed such that, during use, a cooling fluid is directed from
the outside onto the circumference of the pressing roller and/or
onto the end faces of the pressing roller, whereby an additional
cooling effect is provided.
[0025] Advantageous embodiments of the device according to the
invention are depicted below with reference to figures.
[0026] Shown schematically are:
[0027] FIG. 1: a double-belt press,
[0028] FIG. 2: a pressing roller pair before and after the pressure
build-up with heating elements and flat material to be processed
without heating means tracking,
[0029] FIG. 3: a pressing roller pair before and after the pressure
build-up with heating elements and flat material to be processed
with heating element tracking,
[0030] FIG. 4: the principle of heating means tracking with
spacers,
[0031] FIG. 5: the principle of the motorized heating element
tracking,
[0032] FIG. 6: pressing roller with integrated heat-insulating
layer,
[0033] FIG. 7: pressing roller with separate thermal insulation
belt guided around a deflection roller,
[0034] FIG. 8: pressing roller with separate thermal insulation
belt guided around two deflection rollers,
[0035] FIG. 9: a perspective view from the side of a workpiece with
inductively acting heating elements and
[0036] FIG. 10: an inductive heating element encompassing the
workpiece in a side view.
[0037] FIG. 1 shows schematically in a lateral cross section a
double-belt press having an upper press belt 1 and a lower press
belt 2. The endless press belts 1 and 2 are each guided around an
upper drive roller 3 and lower drive roller 4 and around an upper
deflection roller 5 and a lower deflection roller 6, respectively.
Flat material to be processed, not shown here, is guided between a
working strand 7 of the upper press belt 1 and a working strand 8
of the lower press belt 2, which is carried in a transport
direction (from left to right in FIG. 1) by the revolving press
belts 1 and 2. A plurality of pressing roller pairs 9 is arranged
along the working strands 7 and 8, with which the upper working
strand 7 and the lower working strand 8 are pressed against the
flat material to be processed, not shown here. Furthermore, heating
elements, not shown individually in FIG. 1, are arranged along the
working strands 7 and 8 in a main heating zone 10 and in
intermediate heating zones 11, which preferably act inductively. In
this case, either the material of the press belts 1 and 2 is
inductively coupled or the flat material to be processed. A
temperature required for processing the flat material can be
maintained over a long distance due to the plurality of heating
elements and their positioning between the pressing roller pairs 9.
The arrangement depicted here of one intermediate heating zone 11
between two pressing roller pairs 9 is only an example. The number
of intermediate heating zones 11 and the arrangement of the
pressing roller pairs 9 adjacent to the intermediate heating zones
11, for example, individually or in groups of two or more pressing
roller pairs 9, can be designed differently depending on the
requirements of the operation of the double-belt press. As seen in
the transport direction, cooling sections 12 are optionally
arranged at the end of the working strands 7 and 8.
[0038] FIG. 2 schematically shows a pressing roller pair 9 having
an upper pressing roller 13 and a lower pressing roller 14, wherein
in a) the situation before application of a pressing power and in
b) the situation under a certain pressing power is shown. A
workpiece 15 made of flat material to be processed is depicted
schematically between the pressing rollers 13 and 14, wherein the
press belts 7 and 8 (see FIG. 1) taking the workpiece 15 between
them cannot be seen in the illustration. The pressing rollers 13
and 14 comprise an elastically deformable region 16 on their outer
circumference. The contact pressure of the two pressing rollers 13
and 14 is built up symmetrically according to FIG. 2, that is, due
to the flexibility of the elastically deformable region 16, the
axes of rotation 17 and 18 of the pressing rollers 13 and 14 each
move the same distance .DELTA.I towards the workpiece 15; the
vertical position of a center plane 19 of the workpiece 15 is
therefore not changed by the application of the pressing power.
FIG. 2 also schematically shows the position of heating elements
20, as they can be provided in the main heating zone 10 or in the
intermediate heating zones 11 (see FIG. 1). The distance between
these heating elements 20 perpendicular to the center plane 19
remains unchanged despite the shift in the positions of the axes of
rotation 17 and 18 which is generated when the pressing power is
applied. However, a considerable amount of regulation effort has to
be carried out in order to achieve a movement of the pressing
roller pair 13 and 14 symmetrical to the center plane 19.
[0039] FIG. 3 shows a situation similar to FIG. 2. The same
reference numbers relate to the same device elements, so that
reference can be made to the description of FIG. 2. The starting
position of the pressing rollers 13 and 14 shown in partial figure
a) is identical to the starting position in FIG. 2a). One
difference is that the axis of rotation 18 of the lower pressing
roller 14 is fixed in its position in the arrangement according to
FIG. 3. In order to apply the pressing power, only the axis of
rotation 17 of the upper pressing roller is thus moved by a
distance 2.DELTA.I in the direction of the lower axis of rotation
18. Since the deformation of the pressing rollers 13 or 14 is the
same due to the otherwise matching structure, the center plane 19
of the workpiece 15 will move to the lower pressing roller 14 by
the distance .DELTA.I. In order to prevent the application of the
pressing power from changing the effect of the heating elements 20
on the workpiece 15, provision is made not to change the distance
between the heating elements 20 and the center plane 19 and also to
move the heating elements 20 by the distance .DELTA.I. With this
measure, the advantage of the surface pressure achieved by means of
the elastically deformable region 16 is achieved without
restriction due to an otherwise only limitedly reproducible effect
of the heating elements 20 on the workpiece 15.
[0040] FIG. 4 schematically shows, in a cross section perpendicular
to the material transport direction, a double-belt press having two
heating elements 20, one above and the other below the workpiece 15
and the press belts 1 and 2 receiving the workpiece 15 arranged
between them. The heating elements 20 are held on brackets 21 such
that the distance between the respective heating element 20 and the
associated press belt 1 or 2 is as constant as possible during
operation of the double-belt press. Spacers 23 are provided here by
way of example for this purpose. In order to be able to follow a
possible vertical movement of the respective press belt 1 or 2, the
heating elements 20 are pressed with a force in the direction of
the associated press belt 1 or 2, which force is symbolized here in
each case by a spring element 22. For the upper one of the heating
elements 20, said force can also be composed of its weight and a
supporting force counteracting gravitation, wherein the supporting
force is intended to reduce the load on the upper press belt 1. The
spacers 23 are preferably fixed on the respective heating element
20 and can roll off the associated press belt 1 or 2. Of course,
sliding spacers can also be provided as an alternative or in
addition. Guide elements 24 are provided for guiding the brackets
21.
[0041] FIG. 5 also shows in cross section a double-belt press in
which, unlike in FIG. 4, the distance between the heating elements
20 and the workpiece 15 arranged between the press belts 1 and 2 is
set by means of electric motors 25 and linear guides 26. Sensor
values from distance sensors 27, which, for example, measure
mechanically, optically or capacitively, serve as the base variable
for the control or regulation of the electric motors 25 taking
place via a control or regulating device 28.
[0042] FIG. 6 shows schematically a pressing roller 29 which
presses on the upper press belt 1 and has a heat-insulating layer
30 which is fixedly arranged on the outer circumference thereof and
which is applied directly to an elastically deformable region 31 of
the pressing roller. The elastically deformable region 31 in turn
surrounds a hollow cylinder 33 made of a material that is rigid in
comparison, for example, stainless steel. An inner cavity 32 of the
hollow cylinder 33 can be used for the flow of a cooling fluid. The
elastically deformable region 31, for example, made of silicone,
can, for example, have a thickness of 1 to 20 mm, preferably 5 to
15 mm, and a hardness between, for example, 20 Shore A and 65 Shore
A, preferably between 50 Shore A and 60 Shore A.
[0043] FIG. 7 shows a pressing roller 34 in which the
heat-insulating layer is not fixed over the entire circumference
but is implemented by a circumferential belt 35 which rests against
the elastically deformable region 36 only on part of the
circumference thereof and is otherwise guided at a distance from
the pressing roller 34 via a deflection roller 37. There is an
improved possibility of separate cooling of the belt 35 in the
spaced-apart region between the pressing roller 34 and the
deflection roller 37. In addition, the belt 35, which is subject to
wear, is easily exchangeable. FIG. 8 shows a further variant
similar to FIG. 7, in which the belt 35, however, is guided over
two deflection rollers 37, whereby a smaller angle of wrap of the
belt 35 with the press roller 34 is implemented and a better
possibility for cooling can be provided. Reference is made to the
description of FIG. 7 for further details.
[0044] The fact that the pressing rollers do not necessarily have
to be hollow cylinders applies to all embodiments. Other shapes
with or without passages for a cooling fluid are also
conceivable.
[0045] FIG. 9 shows a perspective oblique top view of a workpiece
15 to be processed, wherein of the double belt press, only one
inductively acting first heating element 38 having a connection
element 42 arranged in a main heating zone 10 (see also FIG. 1) and
a respective further inductively acting heating element 39, 40 or
41 having a collective connection element 43 arranged in
intermediate heating zones 11 are shown schematically. In the main
heating zone 10, the first heating element 38 is guided in a
plurality of heating loops on the one hand above the workpiece 15
and on the other hand below the workpiece 15. In the intermediate
heating zones 11, the second heating element 39, the third heating
element 40 and the fourth heating element 41 each comprise a
heating loop above and a heating loop below the workpiece 15. In
the intermediate heating zones 11, more than one heating loop in
each case and different numbers of heating loops in different
intermediate heating zones 11 are also conceivable. The heating
elements 39, 40 and 41 can, as shown in FIG. 9, be supplied with
power and cooling water jointly via the collective connection
element 43 by a preferably controllable alternating current source,
not shown here, or without a collective connection element
individually directly with one controllable alternating current
source each. The latter offers the advantage of individual power
regulation and thus individual heating in the heating zones 11.
[0046] FIG. 10 shows the first heating element 38 guided around the
workpiece 15 with the connection element 42 in a side view. The
representations of FIG. 9 and FIG. 10 differ slightly, particularly
in connection element 42, but this is not intended to be of any
significance here. The connection element 42 is, like the
collective connection element 43 (FIG. 9), prepared for contacting
a preferably controllable alternating current source, not shown
here. The heating loops of the first heating element 38 are
mechanically stabilized with respect to one another using two
parallel cross connectors 44 made of an electrically insulating
material.
[0047] The electrical connection between the upper loops and the
lower loops of the first heating element 38 is implemented by two
transition pieces 45 which are each guided around the edge of the
workpiece 15 on the side facing the connection element 42. On the
side facing away from the transition pieces 45, the first heating
element 38 is open and can thus be guided laterally over the
workpiece 15 or the workpiece 15 can be inserted laterally so that
maintenance or replacement of the first heating module 38 is
possible, even when the workpiece 15 is located in the double-belt
press.
[0048] The illustrated course of the loops of the first heating
element 38 above and below the workpiece leads to the magnetic
fields generated during operation of the first heating element 38
being aligned perpendicular to the center plane of the workpiece
15, that is, magnetic transverse fields are generated. Such
transverse fields can be technically and economically more
efficient when heating flat material, that is, with a large ratio
of material width to material thickness, than longitudinal fields
running parallel to the center plane.
[0049] The statements relating to the first heating element 38 also
apply in a corresponding manner to the further heating elements 39,
40 and 41 in the intermediate heating zones 11.
[0050] Of course, other design variants for the heating elements
are also possible, for example, those in which the part running
under the workpiece 15 and the part running above the workpiece can
be moved independently of one another at least over a certain
distance, for example, in order to be able to implement the
embodiment according to FIG. 5. For this purpose, the two parts can
be associated with separate connection elements, for example, or
the electrical connection between the two components is made via
flexible transition pieces or transition pieces that can be changed
in length. It should be noted that the vertical movement of the
heating elements only requires short distances in the mm or cm
range to ensure a largely constant distance between the heating
element and the workpiece (see, for example, FIGS. 4 and 5).
REFERENCE SYMBOLS LIST
TABLE-US-00001 [0051] 1 upper press belt 2 lower press belt 3 upper
drive roller 4 lower drive roller 5 deflection roller 6 deflection
roller 7 working strand upper press belt 8 working strand lower
press belt 9 pressing roller pair 10 main heating zone 11
intermediate heating zone 12 cooling section 13 upper pressing
roller 14 lower pressing roller 15 workpiece 16 elastically
deformable region 17 axis of rotation 18 axis of rotation 19 center
plane 20 heating element 21 bracket 22 spring element 23 spacers 24
guide element 25 electric motor 26 linear guide 27 distance sensors
28 control or regulating device 29 pressing roller 30 heat
insulating layer 31 elastically deformable region 32 cavity 33
hollow cylinder 34 pressing roller 35 belt 36 elastically
deformable region 37 deflection roller 38 first heating element 39
second heating element 40 third heating element 41 fourth heating
element 42 connection element 43 collective connection element 44
cross connector 45 transition piece
* * * * *